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J. Q, A. SARGENT, OF MANCHESTER, NEW HAMPSHIRE.

Letters Patent No. 81,543, dated August 25; 1868.

IMPROVEMENT IN. STEAM-GENERATORS.

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TO ALL WHOM IT MAY CONCERN Be it known that I, J. Q. A. SARGENT ofManchesteminthe county of Hillsborough, and State of New Hampshire, haveinvented an Improved Steam-Generating Boiler; and I do hereby declarethat the following, taken in connection with the drawings whichaccompany and form part of this specification, is a description of myinvention sufiici'ent to enable those skilled in the art to practise it.7 I

Dhis invention relates 'to matters of detail in the construction ofvertical steam-b0ilers having submerged smoke-boxes, the precise subjectof the invention being stated beyond, in the claim.

The drawing shows, invertical central sectional elevation, a boilerembodying my inventiona denoting the outer shell, 6 thecombustibmchamber, connected by direct vertical tubes 0 with thesmokebox at, from which return-tubes e descend through the space betweenthe shell a and the fire-box b, so as to discharge the volatile productsof combustion, at the base of the boiler, into the space surrounding it,and between the boiler-setting f, from which space the smoke 'and gasescan pass of? to a chimney, through a flue, opening out of said space atany convenient point. 7 v v 7 At the top of the smoke-box is achamberyg, closed at its top, and into which the hot volatile productsof combustion can enter, to ,superheatthe steam contained in the top ofthe boiler, above the water-level,.and

around said chamber g.

The smokebox dis wholly submerged, so that its surface does notcontribute to superheating the steam in the dome of the boiler,thc'water-level being indicated in the drawing at its highest and lowestplanes, and there being combined with the boiler gauge-cocks, as seen atthe right of the drawing, or a glass water-gauge, as seen at the left ofthe drawing, to indicate the height of the Water-level.

In the described construction, it will be seen that the passage, fromthe boiler, of the volatile products of combustion isof sufiicicntlength to reduce the heat of said products nearly to the heat of thegenerated steam,

before allowing the smoke and gases to pass oil to the chimney; also,that the outside of the boiler is protected from the atmosphereby a hot,gaseous jacket, which not only prevents condensation andcoolinga'gajinst the shell of the boiler, but transforms the outersurface of the boiler into eilcctive heating-surface. I

It willalso be seen that, as. the smoke-box d is always submerged, thedanger of explosion, consequent upon allowing its large surface tobecome uncovered and heated, and then flowing it witl1 water,tlinssuddenly generating more steam than the safety-valve can discharge, isavoided; still, by the use of the chamber g, opening out of thesmoke-box, but giving no thoroughfare through it to the gases, there ispresented by said chamber a sufficient surface of moderately-heatedmetal to evaporate all the free water mechanically held insuspension bythe steam above the \vatcr-levehand to slightly superheat the steam.

If desired, the cover or stop for the chamber 9 may be arranged'asavnlvc, capable of being opened to the chimney, when starting a fire,seas to give a direct passage to the smoke until combustion is fairlyestablished in the fire-chamber, when thecovcr or valve will be made tostop the temporary outlet from the chamberg, and the operation of theboiler will then be as described.

I claim a boiler, constructed and arranged substantially asherein setforth.

Q. A. SARGENT.

Witnesses: I

' Gecnen H. TRUE, 0. W. Srannnr.

